place

*send escape packet when changing title, not to be stuck in some
decoder.

*the position in the title is now resetted when we change title to
prevent a title from being unavailable because we're stuck at the end

*fixed a bug with 1-chapter-long title that displayed chapter 0.

*added a _temporary_ field in p_main to know whether the audio stream is
ac3 (ugly). It allows a vlc launched in spdif mode to play mpeg or lpcm
audio.

*cleaned the title property messages to get rid of the ugly stars.